In [1]}, Li et al. used the sub-6 GHz spatial information to help beam selection in a mmWave system by exploiting the feature that the support set of the mmWave channels is a subset of that for the sub-6 GHz channels with the same grid quantization.
In [2]}, Alrabeiah et al. performed beam prediction at mmWave band from the CSI at sub-6 GHz band with the aid of a DNN. Moreover, the authors incorporated the materials' dielectric coefficients at the sub-6 GHz and mmWave bands, which is critical information for the accurate mapping between the sub-6 GHz and mmWave signals.
